(1) Field of the Invention
This invention relates to a compounding oil for polymers. More particularly, the invention relates to a compounding oil for polymers which oil comprises a fraction that is prepared by disproportionating a fraction containing diarylalkanes which is obtained from the process to prepare alkylated monocyclic aromatic hydrocarbons by alkylating monocyclic aromatic hydrocarbons with olefins. The oil according to the present invention can be used as compounding oils such as plasticizer, process oil, thinner, softener and extender for various plastics and elastomers.
(2) Description of the Related Art
The process to prepare alkylbenzenes such as ethylbenzene, ethyltoluene and cumene by alkylating monocyclic aromatic hydrocarbons such as benzene and toluene with olefins such as ethylene and propylene, is industrially put into practice. In succession to this process, for example, ethylbenzene and ethyltoluene are dehydrogenated and the obtained materials are used as monomers for producing styrene type resins. In the case of cumene, it is consumed as a raw material of cumene process phenol.
In the above alkylbenzene preparation, diarylalkanes are produced as by-products besides the mono and polyalkylated reaction products. For example, from the process for preparing ethylbenzene by reacting benzene with ethylene with an alkylation catalyst, heavier by-product oil containing diarylalkanes such as diphenylethane and phenylethylphenylethane is produced as well as ethylbenzene and polyethylbenzene.
Even though this by-product oil is produced in large quantities, it was used only as fuel, or by obtaining a fraction containing diarylalkanes of arbitrary boiling range, it was used as electrical insulating oil or solvent for the dye of pressure-sensitive recording paper (e.g. U.S. Pat. Nos. 4,108,788; 4,111,824; 4,111,825 and 4,228,024).
This by-product oil itself has considerably high boiling points, however, it is too volatile yet as a compounding oil for polymers. Furthermore, because its diffusion velocity in polymers is large, when it is compounded into polymers, bleeding is liable to occur in some polymers. Therefore, the by-product oil has not been used as a compounding oil for polymers besides the abovementioned uses.
Furthermore, as a triaryldialkane, distyrenated xylene that is produced by adding styrene to xylene with sulfuric acid catalyst is known as a plasticizer for polymers (e.g. U.S. Pat. Nos. 3,833,680 and 3,856,740). However, in comparison with its boiling point, the viscosity and pour point are considerably high which fact is not always satisfactory in use.